Photographic sensitizer and method of making same



i I consider this an important .feature of my Patented Apr. 7, 1925.

' UNITED STATES 1,532,814 PATENT OFFICE.

GURNEYO. GUTEKUNST, OF ROCHESTER, NEW YORK, ASSIGNOR TO EASTMAN KODAK COMPANY, OF ROCHESTER, NEW YORK, A CORPORATION OF NEW YORK.

'PHOTOG-RAPHIC SENSITIZER AND METHOD OF MAKING No Drawing.

. To all whom it may concern:

Be it known that I, GU'RNE'Y O. Gurn- KUNST, a citizen of the United States of America, residing at Rochester in the county of Monroe and State of New York, have invented certain new and useful Improvements in Photographic Sensitizers and Methods of Makin Same, of which the following is a full, clear, and exact specification. a

This invention relates to carbocya-nine dyes particularly useful for the sensitization of photographic emulsions to the red and infra-red and to the method of making the same.

-'I have discovered that if a G-acetaminoquinaldine alkylhalide is treated in alcoholic solution with an alkali alcoholate in the presence of a suitable condensing agent and with or without a quinoline alkyl-halide there will be formed a compound capable of sensitizing photographic emulsions in the I extreme infra-red.

The following example will serve to illustrate the invention: A mixture of 5 grams tals separate on cooling. These are recrysi'be used 15 cc. of 10% alcoholic potash instead'of 25 cc. of sodium ethylate, but the tallized from methyl alcohol. This carbocyanine dye sensitizes a photographic emulslon very strongly in the infra-red portion of the spectrum, the maximum efl'ectbeing "about 730p.p., but decreasing very gradually so that it is usefully eifective for a very long range extending beyond 860 There may reaction is not as certain. In any event the water content-of the bath durin tion is maintained as low as practicable, and

invention. I have found that 95% ethyl alcohol may be used instead of absolute alcovhol in the reaction bath, but if the water content is materially greater than 5%, any

.. dyes produced do not sensitize in the infrared to the extent indicated above. I, therefore, consider a 5% water content'to bea critical value. If there is a very high water content, no dyewhatever is yielded. Other the reac- Application filed October 21, 1921. Serial No. 509,438.

red region of the spectrum and produced by the action of a strong base in an alcoholic solution with a low water content on a 6- acetamino-quinaldine alkyl-halide in the presence of a condensing a ent.

2. A carbocyanine dye e ective for sensitizing photographic emulsions in the ultrared region of the spectrum and produced by the action of a strong base in an alcoholic solution with a low water content on a 6- acetainino-quinaldine alkyl-halide in the presence of a condensing agent and of a quinoline alkyl-halide.

3'. A carboc'yanine dye efi'ective for sensitizing photographic emulsions in the ultrared region of the spectrum and having a maximum eifect at about 730w. and produced by the action of sodium ethylate in an alcoholic solution with a low water content on 6-acetamino-quinaldine ethiodide in the presence of quinoline ethiodide and formalehyde. I

4. The process of making a carbocyanine dye by the action of a strong base in an alcoholic solution with a low water content on a 6-acetamino-quinaldine alkyl-halide in the presence of a condensing agent until a dye effective for sensitizing. photographic emulsions and having a maximum effect at about 73044;. is produced.

5. The process of making a carbdcyanine I I dye by the action of a strong base in an alcoholic solution with a low water content on a fi-acetaminoquinaldine alkyl-halide in the presenceof a quinoline alkyl-halide and of a condensing agent until a dye effective for.

sensitizing photographic emulsions and having a maximum effect at about 730p.p is produced.

6. The process of making a carbocyanine dye by the action of an alkali-alcoholate in alcoholic solution on a G-acetamino-quinaldine alkyl-halide in the. presence of a condensing agent until a dye efiective for sensitizing photographic emulsions and having a. maximum efi'ect at about 730m). is produce I The process of making a carbocyanine dye by the action of an alkali-alcoholate in alcoholic solution on a fi-acetamino-quinaldine alkyi-halide in the presence of a, quinoline alkyl-halide and a condensing agent until a dye efie-ctive for sensitizing photographic emulsions and having a, maximum effect at about 730% is produced.

8. The process of making a carbocyanine dye by treatin G-acetaminmquinaldine ethiodide with sodium ethylate in alcoholic solution with a, low Water content in the presence of quinoline ethiodide and formald&

hyde.

GU'RNEY O. GU'LEKUNST. 

